Lignin is a natural polymer, which can be extracted from e.g. wood. As lignin is a natural biopolymer its use as a component in glues instead of synthetic materials has been investigated in order to come up with a more environmentally friendly adhesive composition. Especially, the ability to replace synthetic phenol in phenolic resins, such as phenol formaldehyde resin, has been the object of prior art. Lignin can be used for the purpose of decreasing the amount of synthetic phenol in a resin composition. Lignin has previously been used for replacing phenol during the production of lignin-phenol-formaldehyde resin.
The currently known lignin based resins are not, however, suitable for all the applications where traditional phenolic resins are being used. For example, the currently known lignin based resins are not suitable for high-pressure laminates. High-pressure laminates (HPL), which are also known as plastic laminates, can be produced by fusing together under the influence of heat and pressure, multiple layers of paper, fabrics, or other core materials by using thermosetting resins as binders. The inventors have recognized a need for a method, which would result in a higher phenol replacement in the resin and thus in a more environmentally friendly binder composition having suitable properties for use in different applications such as high-pressure laminates.